Levocetirizine

Products

Levocetirizine is commercially available in the form of film-coated tablets and as drops (Xyzal, generic). It has been approved in many countries since 2001. Levocetirizine is the -enantiomer of cetirizine (Zyrtec, both UCB-Pharma SA). Levocetirizine tablets contain 5 mg of active ingredient; cetirizine tablets contain 10 mg (plus 5 mg of the -enantiomer). Unlike cetirizine, levocetirizine was initially protected by a patent. Generics were first registered in October 2012 and went on sale in 2013. In 2017, over-the-counter tablets were approved in many countries. They go on sale in January 2018 (Allergo-X).

Structure and properties

Levocetirizine (C21H25ClN2O3, Mr = 388.9 g/mol) is the -enantiomer of cetirizine, a racemate of – and -cetirizine. It is present in drugs such as cetirizine as levocetirizine dihydrochloride. Cetirizine is a piperazine derivative and a carboxylic acid metabolite of hydroxizine (Atarax), a 1st generation antihistamine.

Effects

Levocetirizine (ATC R06AE09) has antihistamine, antiallergic, and anti-inflammatory properties. It has high selectivity for the H1 receptor, is not anticholinergic, and is not cardiotoxic. It passes the bloodbrain barrier insignificantly and therefore causes less drowsiness and sleepiness than 1st generation antihistamines; however, both adverse effects may still occur. The onset of action is rapid and long-lasting, so it only needs to be administered once daily. Levocetirizine has a higher affinity for the H1 receptor compared with the -enantiomer and dissociates more slowly.

Indications

Levocetirizine is approved for the treatment of allergic rhinitis, hay fever, allergic conjunctivitis, and chronic idiopathic urticaria.

Contraindications

  • Hypersensitivity
  • Terminal renal failure

For complete precautions, see the drug label.

Interactions

Interactions have been observed with theophylline and ritonavir. Levocetirizine should not be taken with alcohol as a precaution.

Adverse Effects

Possible adverse effects include drowsiness, fatigue, dry mouth, headache, weakness, and hypersensitivity reactions, among other less common side effects.